For many years, a very popular mechanism for reducing lumps or large pieces of various kinds of material to smaller sizes has been either a cylindrical or frusto-conical shell that is circular in cross-section and having opposite ends connected to the shell to form an enclosure for the material to be reduced in size and grinding media, one common form of which has comprised balls formed from different types of material, preferably of a hard nature. The shells comprising said mills are supported at opposite ends for rotation by suitable power means and appropriate inlet and discharge ports are formed in such shells, usually in the opposite ends thereof. Particularly for purposes of preventing the inner surfaces of such shells from being damaged by the rotating material and grinding media, it has been common practice to line the inner surfaces of said shells with wear-resisting devices, usually in the form of arcuate plates or segments extending circumferentially around the inner surfaces of such cylindrical or frusto-conical body and the ends thereof, said plates or segments heretofore having been formed from various kinds of metal alloy selected and designed especially to resist wear during contact thereof with the material being processed and the grinding media which effects such reduction in size. Some typical examples of such structures comprise the subject matter of:
U.S. Pat. No. 1,132,909--Brinton, dated Mar. 23, 1915 PA1 U.S. Pat. No. 1,538,620--Canda, dated May 19, 1925 PA1 U.S. Pat. No. 1,690,493--Marcy, dated Nov. 6, 1928 PA1 U.S. Pat. No. 1,470,597--Denny et al., dated Oct. 16, 1923 PA1 U.S. Pat. No. 1,601,956--Gammeter, dated Oct. 5, 1926 PA1 U.S. Pat. No. 2,058,257--Porteous, dated Oct. 20, 1936
As early as the 1920's, there developed a type of lining formed of rubber compounds formed into suitable configurations, such as longitudinally extending ridges circumferentially spaced from each other and secured to the inner surface of the shell of the mill by appropriate bolts having head portions secured within said rubber lining segments. Possibly either because of the type of rubber then available, or otherwise, such liners did not appear to suitably increase the life of the liner beyond that which was capable of conventional metal liner segments, and as far as is known, the use of such rubber lining devices was not popularly followed. Typical examples of rubber-type linings for rotatable mills are illustrated in the following prior U.S. Patents:
In much more recent times, further refinements in rubber liners have been made which, for example, comprise the subject matter of U.S. Pat. No. 3,318,537 to Wallin et al., dated May 9, 1967, the details of such structure being directed primarily to the joint-forming means between successive panel-like lining elements, as well as the formation of longitudinal ribs thereon of a somewhat rectangular nature in plan view.
In accordance with the present invention, it now has been found that vastly improved wear-resistance can be achieved by the use of presently available synthetic resin or plastic materials from which to form preferred configurations of especially the material-engageable surfaces of such panels, details of which are set forth below: